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Marvell chips for "plug-top computers"

Marvell Kirkwood: ARM SoC with multiple interfaces for home servers
Source: Marvell
Chip manufacturer Marvell is targeting high performance Network Attached Storage (NAS) boxes, home servers and a new class of devices called "plug computers" with its Kirkwood range of highly integrated system-on-chips (SoCs). These integrated chips have ARM cores and multiple integrated controllers – such as SATA/eSATA mass storage media, Gigabit Ethernet, and USB 2.0. Plug computers are network adapters that are permanently switched on and can, for example, provide NAS functionality. Marvell has created a development platform for its Kirkwood chips, called SheevaPlug. According to the Marvell press release "Multiple standard Linux 2.6 kernel distributions are supported on the SheevaPlug development platform enabling rapid application development".

Embedded processors and SoCs with ARM, MIPS or PowerPC cores have already been used in relatively low power and low cost NAS devices before. However, the performance of these processor cores, which often only operate at a clock speed of 200 or 300 MHz, is often inadequate for the potential data transfer rates of more than 100 MBytes/s achievable via Gigabit Ethernet. Such rates have so far mainly been reached with x86 processors, which in most cases require much more expensive hardware and have a much higher power consumption. Intel plans to sell SoCs with Atom cores in the near future and ARM has also announced that it intends to compete in this area.

Low power "plug computers" are designed for continuous operation
Source: Marvell
Marvell's Kirkwood processor looks to be one of Atom's competitors. Its ARM v5TE compatible Sheeva core operates at speeds of 800 MHz to 1.2 GHz and offers both a Memory Management Unit (MMU) and relatively large caches (L1: 16 KBytes each for data and instructions, L2: 256 KBytes/300 MHz). The memory controller can handle DDR2 SDRAM with a speed of up to 400 MHz via 16 data lines. Interfaces and controllers are particularly abundant. Depending on the version of Kirkwood, there are two integrated Gigabit Ethernet MACs (Media Access Controllers), one or two SATA II ports, a USB 2.0 host controller and an SDIO controller for memory cards, as well as a PCI Express x1 cards used for connecting components like a WLAN adapter. The SATA ports can reportedly handle more than two hard disks via port multipliers – which can also be obtained from Marvell.

Depending on its operational state and clock speed, a Kirkwood chip reportedly only needs less than 1 Watt of power; according to the spec sheet, about 1.4 Watts are required for running most of the interfaces simultaneously, along with the Sheeva core running at 1 GHz.

US vendor Cloud Engines has already announced the first "plug computer" called Pogoplug at a pre-order price of $79. For developers, Marvell is offering a SheevaPlug Development Kit for $99.